Stereoscopic display has become a major trend in display field. Basic principle of stereoscopic display is to produce stereoscopic sensation by applying parallax, i.e., make one's left eye see a left-eye picture and right eye see a right-eye picture, where the left-eye picture and the right-eye picture here are a stereoscopic picture pair with parallax.
One way to realize a stereoscopic sensation is to adopt serial display, i.e., at a first moment, a display device displays a left-eye image and only left eye of a watcher is allowed to see the display image; at a second moment, the display device displays a right-eye image and only right eye of the watcher is allowed to see the display image. By utilizing image persistence of one's eye retina, it makes one to feel that both the left and right eye see the left-eye image and right-eye image simultaneously, thereby the stereoscopic sensation is produced.
Another way of realizing the stereoscopic sensation is parallel display, i.e., at the same moment, part of pixels on a display device display content of a left-eye image, and part of pixels display content of a right-eye image. By means of gratings, polarized glasses and the like, the display on one part of pixels can only be seen by right eye, and that on the other part can only be seen by left eye, and thereby the stereoscopic sensation is produced.
Stereoscopic display of polarized glasses type is a major technology in current stereoscopic display field, the basic structure of which is that a device which can adjust polarization direction of emitting light is installed in front of a display panel. The device may be a pattern retarder, and may also be a liquid crystal cell, or other devices that can adjust polarization direction of emitting lights of different pixels. The principle of stereoscopic display by pattern retarder is as shown in FIG. 2. Right-eye images and left-eye images are respectively displayed on every other line on a display panel, and a pattern retarder is placed in front of the display panel, wherein a structure with λ/2 delay for one line and no delay for the other line is repeated, which makes the polarization direction of emitting light of pixels with λ/2 delay rotate 90 degrees. Therefore, wearing polarized glasses with orthogonal polarization directions for the left-eye and the right-eye enables the right eye to see only light emitted from right-eye pixels and enables the left eye to see only light emitted from the left-eye pixels, and thereby a stereoscopic effect is produced.
During various stereoscopic displays by polarized glasses, the technology adopting the pattern retarder is the most preferable. Its basic structure is that a pattern retarder is attached to a display panel with accurate alignment, and different phase retardations are produced by different regions of the pattern retarder, and thereby allowing light of different pixels to be emitted along different polarization directions. A watcher may watch a 3D effect through polarized glasses.
However, the greatest weakness of the above-mentioned 3D display is that a view angle along a vertical direction is very small. FIG. 3 illustrates the principle of the limited viewing angle. In FIG. 3, “a” is the height of a pixel display region, “b” is the width of a black matrix (BM) in the vertical direction, “h” is the distance between a pattern retarder to a display panel, “c” is the width of a strip on the pattern retarder, “0” is the 3D viewing angle, and “p” is the size of a pixel, wherein p=a+b and p is a constant. In FIG. 3, only region “d” can achieve a good 3D effect, wherein the angle “θ” is a key parameter.
By geometry calculation according to the above-mentioned simplified mathematical model, it is obtained that the 3D viewing angle “θ” meets an equation (1):
                              tan          ⁢                                          ⁢                      θ            2                          =                              a            +                          2              ⁢                                                          ⁢              b                        -            c                                2            ⁢                                                  ⁢            h                                              (        1        )            
It can be seen that “θ” increases as the width “b” of the black matrix (blocking bar) increases. As shown in FIG. 4(b), a design of active black matrix (Active BM) has been proposed accordingly. In a structure of active black matrix in FIG. 4(b), which is different from the ordinary pixel structure shown in FIG. 4(a), an original sub-pixel is divided into an upper part and a lower part (for simplicity, they are referred to Part A and Part B herein) for separate control, where in 2D display model, A and B pixels display the same content; and in 3D display model, B pixels display in black, which is equivalent to increasing the BM width (b) of the original pixels, and thereby a 3D viewing angle “θ” is enlarged.
A conventional control method for an active black matrix display panel is to regard Part B as an independent pixel for controlling, thus double gate lines and double data lines comparing with those in the original display panel are needed, and therefore cost and complexity for control are greatly increased.